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Synthesis, Structure, and Solubility Studies of a New Arsenato‐Polyoxovanadate Cluster Compound: (NH 4 ) 4 [V 12 As 8 O 40 (H 2 O)]·4H 2 O
Author(s) -
Wutkowski Adam,
Evers Nils,
Bensch Wolfgang
Publication year - 2011
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.201100330
Subject(s) - orthorhombic crystal system , crystallography , chemistry , band gap , cluster (spacecraft) , solubility , molecule , crystal structure , thermal decomposition , infrared spectroscopy , stereochemistry , materials science , optoelectronics , organic chemistry , computer science , programming language
Abstract. The new arsenato polyxoxvanadate (NH 4 ) 4 [V 12 As 8 O 40 (H 2 O)] · 4H 2 O ( 1 ) was obtained under solvothermal conditions using either a mixture of ethyl ether/H 2 O or ethanol/H 2 O acting as reducing agents. Compound 1 crystallizes in the orthorhombic space group Pnnm with a = 13.6740(3), b = 12.7378(5), c = 13.0580(3) Å, V = 2274.40(11) Å 3 , Z = 2. The central structural motif features an anionic cluster shell, which can be derived from the {V 18 O 42 } archetype cluster by replacing VO 5 polyhedra by As 2 O 5 units and omitting two VO 5 square pyramids. The electronic situation of the cluster anion can be best described by the formula [V 8 IV V 4 V As 8 III O 40 (H 2 O)] 4– . The charge neutrality of the compound is achieved by NH 4 + cations which occupy the free space between the clusters together with crystal H 2 O molecules. Thermal investigation shows a complex decomposition process occurring in at least three steps. Determination of the optical band gap classifies 1 as a semiconductor with a band gap of 2.8 eV. Solubility studies accompanied by IR spectroscopy, ESI‐MS, X‐ray powder diffractometry and elemental analysis demonstrate that the cluster is partially dissolved.